In this chapter, we review our Self-Regulation of Motivation (SRM) model, which identifies the important role that interest plays in students’ motivational experiences. When learning requires persistence and re-engagement over time, activities, and contexts, the ability to maintain motivation becomes a critical self-regulatory task. The SRM model proposes that while motivation to attain goals can be sufficient to start a learning activity, experiencing interest becomes important once engaged. Aspects of the goal striving process (such as goal congruence and the expectancy-value of goals) affect the interest experience, over and above objective activity characteristics. Moreover, when interest is low but reaching a goal is important, students purposely engage in actions that make the experience more interesting (e.g., by making it more congruent with their goals or by exploratory engagement with the activity and context). Further, the ways in which students try to make the experience interesting can influence performance in both positive and negative ways (e.g., potential trade-offs between short-term output and longer-term persistence, re-engagement, and learning). We discuss evidence for this model across a variety of contexts (including online learning and science classrooms) and discuss the implications for understanding group-level differences (e.g., in gender or ethnicity) in students’ interest and motivation.